1. Field of the Invention
This invention relates to N-substituted monomers and polymers, methods of making such monomers and polymers, and methods of using them in various applications, such as medical devices.
2. Description of the Related Art
The tyrosine-derived monomers of U.S. Pat. No. 5,099,060 polymerize to form polymers with higher melt or solution viscosities that may result in poor processibility. As a result, the fabrication of the polymers requires higher temperatures, higher pressures, or both, that are less economical and may also degrade the polymer or any additives (such as biological or pharmaceutical moieties).
Such higher melt or solution viscosities can occur with tyrosine-derived polymers such as the polyiminocarbonates of U.S. Pat. No. 4,980,449, the polycarbonates of U.S. Pat. No. 5,099,060, the polyarylates of U.S. Pat. No. 5,216,115, the poly(alkylene oxide) block copolymers of U.S. Pat. No. 5,658,995, the phosphorous-containing polymers of U.S. Pat. Nos. 5,912,225 and 6,238,687, the anionic polymers of U.S. Pat. No. 6,120,491, the poly(amide carbonates) and poly(ester amides) of U.S. Pat. No. 6,284,862, the radio-opaque polymers of U.S. Pat. No. 6,475,477, and the polyethers of U.S. Pat. No. 6,602,497. The disclosures of all the foregoing patents are incorporated herein by reference in their entirety.
There exists a need for polymers with lower melt viscosities that are capable of being melt-processed and/or solution processed with greater ease, lower temperatures and/or pressures.